Specially designed wear teeth are used in surface removal machines, such as those for removing roadway surfaces. This form of machine generally make use of a rotating cylinder ("mandrel") having spiral flights along the peripheral surface. A plurality of the wear teeth or bits are mounted to the flights by releasable brackets which orient the teeth for engaging and cutting through roadway surface as the mandrel rotates. The teeth are typically removable from the brackets to enable replacement when they become excessively worn. The brackets, in turn, can also be removed from the mandrel flight for replacement when worn.
Efforts have been made to extend the useful life of wear teeth. For example, teeth with cylindrical shanks are commonly mounted in the brackets with locking sleeves within which the teeth are able to rotate. A freely rotatable tooth will not constantly expose a single surface to wear. Instead, the tooth will wear evenly about the periphery of its cutting point as it rotates responsive to rotation of the mandrel and cutting action against the surface to be removed.
The support brackets that mount the teeth also wear significantly and require periodic replacement, though not nearly as frequently as the wear teeth. Replacement of brackets, unlike tooth replacement, requires substantially more "down time" for the equipment. It is a time-consuming and labor-intensive chore to remove and replace brackets, especially those that have been welded in place on the mandrel flights. It is therefore desirable to protect the brackets in a way that will extend their useful life and consequently reduce equipment down time.
My U.S. Pat. No. 4,561,698 discloses a device which can significantly extend the life of the brackets. That patent discloses a bushing and wear protector having an annularly extending flange which covers and protects exposed surfaces of the bracket. Protection of these surfaces reduces bracket wear due to impact and abrasion from the material being removed, and from abrasion and impact from the wear tooth itself. The protector is constructed to wear at approximately the same rate as the tooth, so both the protector and tooth can be replaced at the same interval. My present invention is an improvement upon the inventive concepts disclosed in my U.S. Pat. No. 4,561,698.